All kindergarten, elementary, middle and high schools welcomed students for the first time since schools switched to learning from home or classes being held in shifts since the onset of the Covid-19 pandemic in early 2020, reports Yonhap News Agency.
The full reopening of schools came after the country kicked off the first stage of "living with Covid-19" aimed at gradually bringing the nation back to pre-pandemic normalcy earlier this month.
The government scheduled the reopening of schools for after last week's College Scholastic Ability Test (CSAT).
Parents and teachers have welcomed the return of in-person classes but also voiced concerns over lingering infection risks.
"With offline school activities becoming possible under the in-person class resumption, schools can now take a load off their mind," Kim Chang-soo, principal of Seoul's Hwibong High School, told Yonhap News Agency.
He said his school will resort to a contingency action plan of temporarily turning to two-week e-learning if an infection is reported inside the school.
On Monday, South Korea reported 2,827 new Covid-19 cases, the first daily tally below 3,000 in six days. But the daily number had remained in the quadruple digits since July 7.
The country has recently seen a rise in infection cases involving teenagers, with the inoculation rate remaining very low among them.
Teenagers accounted for 15.4 per cent of the total cases in the fourth week of last month from 11 per cent in the first week, according to health authorities.
As of last week, only 12.8 per cent of those in the 12-17 age range were fully vaccinated against Covid-19 compared to the overall national rate of 78.8 per cent.